Non-nutritive sucking habits, i.e. thumb or pacifier, are very common in children, with reported frequencies ranging from 40-95% below 12 months of age falling gradually with age. Most children have stopped by the age of 6.

Complications that could possibly arise from the habit include dental malocclusions such as narrowing of the upper jaw, callus formation, irritant eczema, paronychia (infection where the nail meets the skin of the finger), and herpetic whitlow. It can also lead to an anterior open-bite, where there is a gap between the top and bottom incisors when the back teeth are together, and an increased overjet, where the upper front teeth protrude. This in turn can make the front teeth more accident-prone, more likely to be damaged or knocked out during a fall. It should be noted that anterior open-bites and increased overjets due solely to sucking habits usually self-correct if the habit stops before 6 years of age.

There is also the possibility of reduced social acceptance by peers, where thumb-suckers are regarded as less intelligent, happy, attractive, likeable, and less desirable as a playmate, and this has often been demonstrated in experimental studies of children of 7 years or older.

It is regarded by developmental psychologists as a normal phenomenon during the first two years of life, and so parents should not be concerned. At this stage the habit should not be discouraged, rather the parents need to make certain that their child is receiving an adequate amount and duration of nursing and feeding. If the habit persists between 3-4 years of age there may be underlying emotional stress such as boredom, tiredness, frustration or unhappiness, and parents need to minimise stress, provide a warm and caring emotional environment, and sufficient stimulation to prevent boredom. Threats or punishment for thumb sucking will not be helpful. If you find your child sucking while asleep, then gently remove the thumb, but almost certainly it will quickly find its way back into the mouth! Be relaxed, and accept the situation.

If the child is 6 years or older, the habit can be reduced or stopped altogether in many cases by simple behaviour modification exercises. Rather than criticising for the act of sucking, which can be interpreted as punishment, reward a period of not sucking with a hug, an appropriate treat, or allowing to watch a favourite TV programme. That reward is more effective when linked with a verbal explanation of why it is being given, and the period of non-sucking needs to be gradually extended before the reward is given, for true progress to be made.

Similarly, studies have shown great success when,  while reading to the child at bedtime, or allowing to watch a favourite TV programme, as soon as the habit starts then the reading stops or the TV is switched off, only to be re-started straight away when the thumb comes out of the mouth. Again these were more effective when a verbal explanation was also given. Both of those approaches seemed to be more effective than painting bitter-tasting substances onto the thumb.

Whichever approach is used it is important that the child receives strong emotional support throughout, in the form of a hug or compliment.

Sometimes the habit becomes so ingrained that the older child is reluctant to give it up, and even treatment involving fixed orthodontic appliances to make it harder to obtain the same satisfaction from the act of sucking, do not work in the long term. Persistence with the habit after these approaches should be discussed with the paediatrician or paediatric dentist.